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Structural Screws / LOK line FAQs
What is a “Structural” Wood Screw?

The simple definition is it is wood screw used to make structural connections. The physical characteristics and strengths of a wood screw making a structural connection must be clearly spelled out and assured by manufacturing and quality controls.

How is a structural wood screw different from a lag bolt?

Unlike lag bolts, structural wood screws must meet stringent engineering and quality standards. They are made from high quality, high strength steel and are heat treated to further enhance their strength.

The appearance of structural wood screws can be deceiving. They are thinner and sharper than a lag bolt. This allows them to be used without predrilling and further enhances the strength of the connection.

What are the advantages of using a structural wood screw over a lag screw?

Lag bolts require the wood to be predrilled twice to install them properly. If not installed properly lag bolts can split the wood either during installation or after and weaken the connection. While the cost of each structural wood screw may be higher, the installed cost, taking labor costs into account, of a structural wood screw is much lower.

What is a “LOK”?

“LOK” is FastenMaster’s line of structural wood products. The idea of making and “LOKing” a connection is key. All these products were developed with the “Faster, Easier, Stronger” theme in mind. Considerable thought has gone into each products engineering and suggested applications. Many have technical bulletins showing you how to use them in common applications and maybe some new ways you may not have thought of.

Why are LOKs painted different colors?

We use different color paint and imprinted numbers on the heads of our LOKs to help users and code officials identify them. LedgerLOKs are gray, TrussLOKs are red, TrussLOK-Zs are blue and TimberLOKs are black. The number stamped on each head gives its length in inches so its length can be verified without removing the fastener.

Why do all the “LOKs” have very different thread lengths and types?

With the exception of TimberLOKs and HeadLOKs all our LOKs are designed for specific purposes. It doesn’t mean they can’t be used for other purposes but their design has been optimized to for particular common connections.

What is ThruLOK?

ThruLOK is a faster, easier, stronger approach to the carriage and hex head bolts with its nuts and washers. ThruLOK requires no predrilling and only a drill to drive the fastener in. Please visit our ThruLOK FAQ page here, download our technical bulletins and view our video.

What does TrussLOK do?

The TrussLOK (the red screw), for instance, for designed for joining only engineered wood products together. Its usage in sawn lumber is not recommended. The threads have wings which break up the fibers in the LVL to reduce the chance of splits in the beam. It is available in three lengths specifically designed to join either 2, 3 or 4 LVLs together. FastenMaster has published a technical bulletin which gives detailed instructions and a video showing its usage.

What is LedgerLOK used for?

The TrussLOK-Z (blue screw), was designed to join multiple plies of 2X lumber together. This is commonly done when ganging up 2X plies for girder trusses, floor joists or vertical studs/beams. It’s short thread and long shank is designed to clamp the plies together, prevent board jacking and keep the stronger shank between the plies for maximum strength.

What is a TimberLOK fastener?

The TimberLOK is the duct tape of FastenMaster’s LOK line. It is available in common sizes. The TimberLOK’s small size is deceptive compared to its strength. One of the most interesting of uses for the TimberLOK is attaching a rafter or a truss to a double top plate of a wall. In most cases a single TimberLOK can replace a hurricane tie and the 10 nails it uses. The technical bulletins and video are found here.

What is a HeadLOK fastener?

The HeadLOK is a version of a TimberLOK with a 5/8” diameter disc type head. It uses a spider drive recess and driver bit which are supplied with the fasteners. HeadLOK is also available in versions for various thicknesses of steel. HeadLOKs can be used nearly any place a TimberLOK can. It is particularly useful to fasten structural insulated panels and fasten rigid foam during deep energy retrofits. You may download a copy of the deep energy retrofit here.

What are OlyLog and LogHog?

These are log fasteners used to fasten logs to each other. OlyLogs are long TimberLOKs packaged in large quantities to suit the needs of log home builders.

LogHogs can be considered the OlyLog’s big brother and is designed for heavy-duty log construction. Both OlyLog and LogHogs have many other uses.

Are your “LOKs” ok to use in pressure treated wood?

In June of 2009 extensive corrosion testing by Louisiana State University’s Wood Durability Laboratory (LSU-WDL) was completed and it concluded the platings, coatings and finishes on our fasteners were superior to hot dipped galvanized plating.

The LSU-WDL is accredited by the International Accreditation Service (IAS), the laboratory accreditation division of the International Code Council (ICC), for testing to the new ICC’s specification AC-257 titled Acceptance Criteria for Corrosion-Resistant Fasteners and Evaluation of Corrosion Effects of Wood Treatment Chemicals.

This testing was also reviewed by an independent Professional Engineer. You may download the corrosion report, the engineer’s review and the labs certification here.

Are your “LOKs” ok to use in fire retardant wood?

Fire Retardants for wood, whether applied by pressure impregnation at a treatment plant or by manual application after construction, come in a multitude of formulations from many manufacturers. This complex and constantly changing spectrum of products makes a broad affirmation of the use of FastenMaster fasteners with every fire retardant and in every application impossible.

All of the fasteners we manufacture are engineered, tested, approved and guaranteed for use in the very corrosive wood preservative ACQ (Alkaline Copper Quaternary). The general consensus is that most fire retardant treatments are far less corrosive than ACQ.

We strongly recommend when specifying a Fire Retardant Treated Wood or a treatment applied after construction the manufacturer’s literature be consulted for the latest information regarding its corrosive effects on fasteners.

As an example, the very popular Dricon® FRT Lumber is found in the International Code Council’s (ICC) Report ESR-1626. In paragraph 3.4 of this report titled “Corrosion”, it states “The corrosion rate of aluminum, carbon steel, galvanized steel, copper or red brass in contact with wood is not increased by Dricon® fire-retardant treatment when the product is used by the manufacturer.”

In the ICC-ESR Report for another widely used Fire Retardant Treated Wood, PYRO-GUARD® made by Hoover Treated Wood Products, Inc., it states in paragraph 3.4 “The corrosion rate of aluminum, carbon steel, galvanized steel, copper or red brass in contact with wood is not increased by PYRO-GUARD® fire retardant treatment when the product is used as recommended by Hoover Treated Wood Products.

This information is found in their technical literature, product brochure or the ICC ESR for their product usually available on their website.

Where do I get driver bits for LOK products?

All LOK products have the proper number and type of driver bits supplied in the box. If for some reason they are missing or lost please call FastenMaster and we can arrange to get them for you.

What is an ICC ESR report?

A ICC ESR Report is a document giving the physical characteristics, design information and strengths for all our fasteners. The ICC or the International Code Council’s (ICC) is an organization which writes most of the building codes for the US.

This ESR or Evaluation Service Report is their report on our products. Having one of these reports means your firm and products undergo a rigorous periodic audit. At this time our ESR numbered ESR-1078 is under continuation.

Where are “LOKs” made?

All our LOK products are manufactured in the US and most are made in Agawam, Massachusetts.

Are LOKs guaranteed?

Yes, each LOK product has it’s own Guarantee of Performance. These documents are available on each product’s page.